CN115087624A - Method for manufacturing optical fiber preform and heating furnace - Google Patents
Method for manufacturing optical fiber preform and heating furnace Download PDFInfo
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- CN115087624A CN115087624A CN202180012420.XA CN202180012420A CN115087624A CN 115087624 A CN115087624 A CN 115087624A CN 202180012420 A CN202180012420 A CN 202180012420A CN 115087624 A CN115087624 A CN 115087624A
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- 239000013307 optical fiber Substances 0.000 title claims abstract description 35
- 238000010438 heat treatment Methods 0.000 title claims abstract description 30
- 238000000034 method Methods 0.000 title claims abstract description 22
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 14
- 239000000463 material Substances 0.000 claims abstract description 27
- 239000007789 gas Substances 0.000 claims abstract description 18
- 238000003860 storage Methods 0.000 claims abstract description 14
- 239000011261 inert gas Substances 0.000 claims abstract description 11
- 238000005245 sintering Methods 0.000 description 12
- 230000007423 decrease Effects 0.000 description 4
- 230000002093 peripheral effect Effects 0.000 description 4
- 230000018044 dehydration Effects 0.000 description 3
- 238000006297 dehydration reaction Methods 0.000 description 3
- 239000011521 glass Substances 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000007062 hydrolysis Effects 0.000 description 2
- 238000006460 hydrolysis reaction Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000002019 doping agent Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000011859 microparticle Substances 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000011282 treatment Methods 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
- 239000012808 vapor phase Substances 0.000 description 1
Images
Classifications
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Manufacture, Treatment Of Glass Fibers (AREA)
Abstract
In a method for manufacturing an optical fiber preform, a heating furnace is prepared, the heating furnace including: a furnace core tube; a heater for heating the untreated base material from the outside of the core tube; a storage chamber for storing a heater; a differential pressure gauge for measuring a differential pressure Δ P (P1-P2) between an internal pressure P1 of the muffle tube and an internal pressure P2 of the storage chamber; the first exhaust pipe and the second exhaust pipe are connected with the furnace core pipe; a throttle valve that restricts a flow rate of exhaust gas passing through the first exhaust pipe; and an opening/closing valve that switches opening/closing of the second exhaust pipe. The inert gas is supplied to the furnace core tube, the flow rate of the throttle valve is set so that the differential pressure delta P is increased when the opening and closing valve is closed, the opening and closing valve is opened when the differential pressure delta P reaches a predetermined upper limit value, and the opening and closing valve is closed when the differential pressure delta P reaches a predetermined lower limit value.
Description
Technical Field
The present invention relates to a method for manufacturing an optical fiber preform and a heating furnace.
This application claims priority based on Japanese patent application No. 2020-054118, 3/25/2020, and the content thereof is incorporated in the present specification.
Background
Patent document 1 discloses a core tube for heating an optical fiber preform to sinter and dehydrate the optical fiber preform. The furnace core pipe is connected with: a supply path for inert gas, and an exhaust path for exhausting unnecessary gas. An electromagnetic valve is provided in the exhaust path, and the amount of opening and closing of the electromagnetic valve is controlled based on the furnace muffle tube internal pressure measured by a differential pressure gauge.
Documents of the prior art
Patent document
Patent document 1: japanese patent laid-open No. 2000-169173
Disclosure of Invention
Technical problem to be solved
In the method of controlling the opening/closing amount of the solenoid valve as in patent document 1, the time required to drive the solenoid valve to the target opening/closing amount tends to be long, and there is room for improvement in response speed. If the response speed of the electromagnetic valve does not satisfy the requirement, the internal pressure of the muffle tube may not be appropriately controlled, and the quality of the optical fiber preform may be unstable.
The present invention has been made in view of such circumstances, and provides a method and a heating furnace for manufacturing an optical fiber preform, which can improve the response speed of a valve provided in an exhaust path and stabilize the quality of the optical fiber preform.
(II) technical scheme
In a method for manufacturing an optical fiber preform according to a first aspect of the present invention, a heating furnace is prepared, the heating furnace including: a core tube having an opening into which an unprocessed base material can be inserted; a heater for heating the untreated base material from the outside of the muffle tube; a housing chamber housing the heater; a differential pressure gauge for measuring a differential pressure Δ P (P1-P2) between an internal pressure P1 of the muffle tube and an internal pressure P2 of the storage chamber; a first exhaust pipe and a second exhaust pipe connected to the core pipe; a throttle valve that restricts a flow rate of exhaust gas passing through the first exhaust pipe; and an on-off valve that switches opening and closing of the second exhaust pipe, supplies inert gas to the muffle tube, sets a flow rate of the throttle valve such that the differential pressure Δ P increases when the on-off valve is closed, opens the on-off valve when the differential pressure Δ P reaches a predetermined upper limit value, and closes the on-off valve when the differential pressure Δ P reaches a predetermined lower limit value.
A heating furnace according to a second aspect of the present invention includes: a core tube having an opening into which an unprocessed base material can be inserted; a heater for heating the untreated base material from the outside of the muffle tube; a housing chamber housing the heater; a differential pressure gauge for measuring a differential pressure Δ P (P1-P2) between an internal pressure P1 of the muffle tube and an internal pressure P2 of the storage chamber; a first exhaust pipe and a second exhaust pipe connected to the core pipe; a throttle valve that restricts a flow rate of exhaust gas passing through the first exhaust pipe; an opening/closing valve that switches opening/closing of the second exhaust pipe; and a control unit that controls the on-off valve and sets a flow rate of the throttle valve such that the differential pressure Δ P increases when the on-off valve is closed, wherein the control unit is configured to open the on-off valve when the differential pressure Δ P reaches a predetermined upper limit value and close the on-off valve when the differential pressure Δ P reaches a predetermined lower limit value.
(III) advantageous effects
According to the above aspect of the present invention, the response speed of the valve provided in the exhaust path can be increased, and the quality of the optical fiber preform can be stabilized.
Drawings
Fig. 1 is a schematic view of a heating furnace of the present embodiment.
Fig. 2 is a diagram for explaining the control content of the open/close valve according to the present embodiment.
Detailed Description
Hereinafter, a heating furnace according to the present embodiment and a method for manufacturing an optical fiber preform using the heating furnace will be described with reference to the drawings.
As shown in fig. 1, the heating furnace 1 includes a muffle tube 2, a heater 3, a storage chamber 4, a differential pressure gauge 5, an exhaust passage 6, a throttle valve 7, an opening/closing valve 8, a control unit 9, and a supply passage 10.
The muffle tube 2 is formed in a bottomed cylindrical shape and has an opening 2a at an upper end. The optical fiber preform M can be inserted into the core tube 2 or taken out from the core tube 2 through the opening 2 a. The muffle tube 2 is formed of quartz glass in order to prevent impurities from being mixed into the optical fiber preform M.
The heater 3 is disposed on the outer periphery of the core tube 2, and configured to heat the optical fiber preform M together with the core tube 2. The heater 3 is disposed in the housing chamber 4 and is isolated from the outside air.
The differential pressure gauge 5 is connected to the muffle tube 2 and the storage chamber 4, and is configured to measure a differential pressure Δ P (P1-P2) between an internal pressure P1 of the muffle tube 2 and an internal pressure P2 of the storage chamber 4.
The exhaust path 6 is connected to the muffle tube 2 and configured to exhaust unnecessary exhaust gas in the muffle tube 2. In the example of fig. 1, the exhaust passage 6 includes a connection portion 6a, a first exhaust pipe 6b, and a second exhaust pipe 6 c. One end of the connecting portion 6a is connected to the muffle tube 2, and the other end is connected to the first exhaust pipe 6b and the second exhaust pipe 6 c. In other words, the first exhaust pipe 6b and the second exhaust pipe 6c are branched from the connecting portion 6a and are indirectly connected to the muffle tube 2. Instead of the connection portion 6a, the first exhaust pipe 6b and the second exhaust pipe 6c may be directly connected to the muffle tube 2.
The throttle valve 7 is provided in the first exhaust pipe 6b, and is configured to restrict the flow of the exhaust gas passing through the first exhaust pipe 6b to a predetermined flow rate (hereinafter referred to as a first flow rate F1). The first flow rate F1 may be set manually or by electric control. However, the value of the first flow rate F1 was kept constant during the sintering process and the dehydration process. Details of the first flow rate F1 will be described later.
The on-off valve 8 is provided in the second exhaust pipe 6c, and is configured to switch the opening and closing of the second exhaust pipe 6 c. When the opening/closing valve 8 is opened, a predetermined flow rate (hereinafter referred to as a second flow rate F2) of exhaust gas can be discharged from the second exhaust pipe 6 c. On the other hand, when the on-off valve 8 is closed, the exhaust gas cannot be discharged from the second exhaust pipe 6 c. If the flow rate of the exhaust gas discharged from the entire exhaust passage 6 is denoted by F, F is F1+ F2 when the open-close valve 8 is open, and F is F1 when the open-close valve 8 is closed. That is, the flow rate F of the exhaust gas discharged from the exhaust passage 6 becomes large when the opening/closing valve 8 is open, and becomes small when the opening/closing valve 8 is closed.
The control unit 9 is electrically connected to the differential pressure gauge 5 and the on-off valve 8, and is configured to control the on-off valve 8 to open and close based on the value of the differential pressure Δ P measured by the differential pressure gauge 5. As the control unit 9, for example, an Integrated Circuit such as a microcontroller, an IC (Integrated Circuit), an LSI (Large-scale Integrated Circuit), or an ASIC (Application Specific Integrated Circuit) may be used. The opening/closing valve 8 is configured to open or close the second exhaust pipe 6c in accordance with a command (control signal or the like) output from the control unit 9.
The first end of the supply path 10 is connected to the muffle tube 2, and the second end is connected to a supply source of inert gas. As the inert gas, helium (He), argon (Ar), or the like can be used. The supply path 10 is configured to supply an inert gas into the muffle tube 2. In fig. 1, the supply path 10 is connected to the bottom wall of the core pipe 2, but the supply path 10 may be connected to the peripheral wall of the core pipe 2.
Next, a method for manufacturing the optical fiber preform will be described. In the present embodiment, a case of using a flame hydrolysis method (japanese: スート method) such as a VAD method (Vapor-phase Axial Deposition method) or an OVD method (Outside Vapor Deposition method) will be described, but other methods may be used.
In the production of an optical fiber preform by flame hydrolysis, first, oxygen, hydrogen, inert gas, and the like are passed through a burner installed in a reaction vessel not shown, and SiCl is introduced into a flame in which these gases react 4 And the like glass raw material gas. Thereby producing glass microparticles. By attaching the glass fine particles to a reaction vesselRotating the target in the container, thereby accumulating loose bodies on the periphery of the target. Thus, the optical fiber base material M before sintering (hereinafter referred to as an untreated base material M) is obtained.
Subsequently, the unprocessed base material M is lowered while being rotated, and inserted into the muffle tube 2 through the opening 2 a.
Subsequently, the untreated base material M is heated by the heater 3 while supplying the inert gas from the supply path 10. Thus, the untreated base material M is gradually heated from the lower portion to the upper portion thereof, and the porous body is sintered (sintering step). Thus, the optical fiber base material M after sintering is obtained. The dehydration step may be performed at the time of or before the sintering step. The doping step of adding the dopant to the optical fiber base material M may be performed before or simultaneously with the sintering step.
Further, the optical fiber is obtained by drawing the optical fiber base material M taken out from the heating furnace 1.
Here, when the heater 3 heats the optical fiber base material M, the peripheral wall of the core tube 2 is also heated at the same time. Since the muffle tube 2 is formed of quartz glass, it is softened to some extent by heating. Therefore, when the differential pressure Δ P becomes a negative value, the peripheral wall of the muffle tube 2 is deformed inward, which may degrade the quality of the optical fiber preform M. Therefore, the differential pressure Δ P is required to keep a positive value. On the other hand, even if the differential pressure Δ P is a positive value, if the value is too large, the peripheral wall of the muffle tube 2 may expand outward or be damaged.
Therefore, in the present embodiment, the flow rate setting of the throttle valve 7 and the opening/closing operation of the opening/closing valve 8 are performed so that the value of the differential pressure Δ P does not become a negative value and does not exceed a predetermined upper limit value. Hereinafter, the description will be made in more detail with reference to fig. 2.
The horizontal axes of (a) and (b) in fig. 2 represent time. The vertical axis of fig. 2 (a) represents the differential pressure Δ P measured by the differential pressure gauge 5. The vertical axis of fig. 2 (b) represents the flow rate F of the exhaust gas discharged through the exhaust passage 6.
At the time when t becomes 0, the opening/closing valve 8 is closed, so F becomes F1. The flow rate F1 of the throttle valve 7 is set such that the differential pressure Δ P rises when the on-off valve 8 is closed. Therefore, as shown in fig. 2 (a), the differential pressure Δ P increases while t is between 0 and t 1. Note that the value of the differential pressure Δ P at the time when t becomes 0 may not be the lower limit value L2 as shown in fig. 2 (a) as long as it is a positive value.
The control unit 9 is configured to output a command to open the opening/closing valve 8 when the differential pressure Δ P increases and reaches a predetermined upper limit value L1. Therefore, as shown in fig. 2 (a) and (b), when the differential pressure Δ P increases to the upper limit value L1 (t is t1), the control unit 9 opens the on-off valve 8, and the flow rate F increases to F1+ F2. During the period from t1 to t2, the flow rate increases to F1+ F2, and the differential pressure Δ P decreases.
The control unit 9 is configured to output a command to close the on-off valve 8 when the differential pressure Δ P decreases and reaches a predetermined lower limit value L2. Therefore, as shown in fig. 2 (a) and (b), when the differential pressure Δ P decreases to the lower limit value L2 (t is t2), the on-off valve 8 is closed by the controller 9, and the flow rate F returns to F1. During the period from t2 to t3, the flow rate returns to F1, and the differential pressure Δ P rises again.
Similarly, when the differential pressure Δ P reaches the upper limit value L1, the controller 9 opens the on-off valve 8 (t is t3), and when the differential pressure Δ P reaches the lower limit value L2, the controller 9 closes the on-off valve 8 (t is t 4). The same operation is repeated after time t is t4, and the illustration is omitted.
As shown in fig. 2 (a), in the present specification, the time from opening of the on-off valve 8 to closing of the on-off valve 8 is represented by Δ T1, and the time from closing of the on-off valve 8 to opening of the on-off valve 8 is represented by Δ T2.
The value of Δ T1 is determined based on the flow rate of the inert gas supplied to the muffle tube 2 through the supply path 10 (hereinafter referred to as the supply flow rate), the allowable flow rates of the first exhaust pipe 6b (based on the setting of the throttle valve 7) and the second exhaust pipe 6c, the upper limit value L1 and the lower limit value L2, and the like.
The value of Δ T2 is determined according to the supply flow rate, the allowable flow rates of the first exhaust pipe 6b and the second exhaust pipe 6c, the upper limit value L1, the lower limit value L2, and the like.
The values of Δ T1 and Δ T2 may vary between one sintering step and one dehydration step.
The value of Δ T1 is preferably in the range of 0.25 to 1 minute, for example. The value of Δ T2 is preferably in the range of 1 to 10 minutes. By setting appropriate values of Δ T1 and Δ T2, the frequency of operation of the on-off valve 8 in the primary sintering step can be appropriately set, and it is possible to suppress the differential pressure Δ P from accidentally exceeding the upper limit value L1 or falling below the lower limit value L2.
As described above, in the method for manufacturing an optical fiber preform according to the present embodiment, the heating furnace 1 is prepared, and the heating furnace 1 includes: a core tube 2 having an opening 2a into which an untreated base material can be inserted; a heater 3 for heating the untreated base material from the outside of the muffle tube 2; a storage chamber 4 for storing the heater 3; a differential pressure gauge 5 for measuring a differential pressure Δ P (P1-P2) between the internal pressure P1 of the muffle tube 2 and the internal pressure P2 of the storage chamber 4; a first exhaust pipe 6b and a second exhaust pipe 6c connected to the muffle tube 2; a throttle valve 7 that restricts the flow rate of exhaust gas passing through the first exhaust pipe 6 b; and an on-off valve 8 that switches the opening and closing of the second exhaust pipe 6 c.
Then, the inert gas is supplied to the muffle tube 2, the flow rate of the throttle valve 7 is set so that the differential pressure Δ P rises with the on-off valve 8 closed, the on-off valve 8 is opened when the differential pressure Δ P reaches a predetermined upper limit value L1, and the on-off valve 8 is closed when the differential pressure Δ P reaches a predetermined lower limit value L2.
With such a configuration, the differential pressure Δ P can be maintained within the range between the predetermined upper limit value L1 and lower limit value L2 by a simple control content of opening and closing the opening/closing valve 8. Since the on-off valve 8 is simply operated to open and close, the response speed can be increased and the quality of the optical fiber preform can be stabilized as compared with a valve of a system in which the flow rate is controlled based on the differential pressure Δ P. By setting lower limit value L2 to a value equal to or greater than zero, it is possible to easily prevent differential pressure Δ P from becoming a negative value.
The time Δ T1 from the opening of the on-off valve 8 to the closing of the on-off valve 8 may be in the range of 0.25 to 1 minute. By setting Δ T1 to 0.25 minutes (15 seconds) or more, the response speed of the on-off valve 8 is suppressed from being too slow with respect to Δ T1, and the control of the differential pressure Δ P can be prevented from being unstable. By setting the allowable flow rate of the second exhaust pipe 6c (the inner diameter of the second exhaust pipe 6c, etc.) so that Δ T1 is 1 minute or less, for example, when the differential pressure Δ T is excessively large, exhaust gas can be quickly discharged.
The time Δ T2 from the closing of the on-off valve 8 to the opening of the on-off valve 8 may be in the range of 1 to 10 minutes. By setting Δ T2 to 1 minute or more, the frequency of operation of the opening/closing valve 8 during the primary sintering step can be suppressed from becoming too high. Therefore, the opening/closing valve 8 can be suppressed from malfunctioning. Further, by setting Δ T2 to 10 minutes or less, the increase in differential pressure Δ T when opening/closing valve 8 is closed can be made more reliably positive for a certain period of time. That is, the following can be suppressed: although the opening/closing valve 8 is closed, the differential pressure Δ T decreases, and the differential pressure Δ T becomes a negative value, which adversely affects the quality of the optical fiber preform.
The lower limit L2 of the differential pressure Δ P may be 50Pa or more. At this time, for example, even if a time lag occurs between the output of the command from the control unit 9 and the actual closing of the on-off valve 8 due to the response speed of the on-off valve 8, the differential pressure Δ P can be suppressed from becoming a negative value.
The heating furnace 1 of the present embodiment includes: a core tube 2 having an opening 2a into which an untreated base material can be inserted; a heater 3 for heating the untreated base material from the outside of the muffle tube 2; a storage chamber 4 for storing the heater 3; a differential pressure gauge 5 for measuring a differential pressure Δ P (P1-P2) between the internal pressure P1 of the muffle tube 2 and the internal pressure P2 of the storage chamber 4; a first exhaust pipe 6b and a second exhaust pipe 6c connected to the muffle tube 2; a throttle valve 7 that restricts the flow rate of exhaust gas passing through the first exhaust pipe 6 b; an opening/closing valve 8 that switches the opening/closing of the second exhaust pipe 6 c; and a control unit 9 that controls the on-off valve 8.
The flow rate of the throttle valve 7 is set so that the differential pressure Δ P rises with the on-off valve 8 closed, and the controller 9 is configured to open the on-off valve 8 when the differential pressure Δ P reaches a predetermined upper limit value L1 and close the on-off valve 8 when the differential pressure Δ P reaches a predetermined lower limit value L2.
By using the on-off valve 8 that is simply opened and closed in this way, the response speed can be increased and the quality of the optical fiber preform can be stabilized, as compared with the case of using a valve of a system that controls the flow rate based on the differential pressure Δ P.
The technical scope of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.
For example, the numerical values of the lower limit values L2, Δ T1, Δ T2 and the like described in the above embodiments are merely examples and may be appropriately changed.
In addition, the components in the above-described embodiments may be replaced with known components as appropriate without departing from the scope of the present invention, and the above-described embodiments and modifications may be combined as appropriate.
For example, although the sintering step is mainly described in the above embodiment, the above embodiment may be applied to a step other than the sintering step performed when the optical fiber base material is manufactured. That is, the "untreated base material" may be an optical fiber base material before sintering (an unsintered base material), or may be an optical fiber base material before other treatments are performed. In addition, the above-described embodiment can also be applied to a case where several steps are continuously performed.
Description of the reference numerals
1-heating a furnace; 2-furnace core tube; 2 a-an opening; 3-a heater; 4-a storage chamber; 5-differential pressure gauge; 6 b-a first exhaust pipe; 6 c-a second exhaust pipe; 7-a throttle valve; 8-an opening and closing valve; 9-a control section.
Claims (5)
1. A method for manufacturing an optical fiber preform,
preparing a heating furnace, the heating furnace comprising: a furnace core tube having an opening into which an untreated base material can be inserted; a heater for heating the untreated base material from the outside of the muffle tube; a housing chamber housing the heater; a differential pressure gauge for measuring a differential pressure Δ P (P1-P2) between an internal pressure P1 of the muffle tube and an internal pressure P2 of the storage chamber; a first exhaust pipe and a second exhaust pipe connected to the core pipe; a throttle valve that restricts a flow rate of exhaust gas passing through the first exhaust pipe; and an opening/closing valve for switching the opening/closing of the second exhaust pipe,
supplying an inert gas to the core tube,
the flow rate through the throttle valve is set so that the differential pressure deltap rises with the on-off valve closed,
opening the opening and closing valve when the differential pressure deltap reaches a prescribed upper limit value,
the opening and closing valve is closed when the differential pressure Δ P reaches a prescribed lower limit value.
2. The method for manufacturing an optical fiber preform according to claim 1,
the time from opening the open/close valve to closing the open/close valve is in the range of 0.25 to 1 minute.
3. The method for manufacturing an optical fiber preform according to claim 1 or 2,
the time from closing the on-off valve to opening the on-off valve is within the range of 1 to 10 minutes.
4. The method for manufacturing an optical fiber preform according to any one of claims 1 to 3,
the lower limit value is 50Pa or more.
5. A heating furnace is provided with:
a core tube having an opening into which an unprocessed base material can be inserted;
a heater for heating the untreated base material from the outside of the muffle tube;
a housing chamber housing the heater;
a differential pressure gauge for measuring a differential pressure Δ P (P1-P2) between an internal pressure P1 of the muffle tube and an internal pressure P2 of the storage chamber;
a first exhaust pipe and a second exhaust pipe connected to the core pipe;
a throttle valve that restricts a flow rate of exhaust gas passing through the first exhaust pipe;
an on-off valve that switches opening and closing of the second exhaust pipe; and
a control unit for controlling the opening/closing valve,
the flow rate through the throttle valve is set so that the differential pressure deltap rises with the on-off valve closed,
the control unit is configured to open the on-off valve when the differential pressure Δ P reaches a predetermined upper limit value, and to close the on-off valve when the differential pressure Δ P reaches a predetermined lower limit value.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2020-054118 | 2020-03-25 | ||
| JP2020054118 | 2020-03-25 | ||
| PCT/JP2021/000768 WO2021192500A1 (en) | 2020-03-25 | 2021-01-13 | Method for manufacturing optical fiber preform, and heating furnace |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN115087624A true CN115087624A (en) | 2022-09-20 |
| CN115087624B CN115087624B (en) | 2024-01-02 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202180012420.XA Active CN115087624B (en) | 2020-03-25 | 2021-01-13 | Method for manufacturing optical fiber preform and heating furnace |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JP7397169B2 (en) |
| CN (1) | CN115087624B (en) |
| WO (1) | WO2021192500A1 (en) |
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| JP2000169173A (en) | 1998-12-01 | 2000-06-20 | Fujikura Ltd | Internal pressure controller for quartz core pipe |
| JP6413293B2 (en) | 2014-03-27 | 2018-10-31 | 東京エレクトロン株式会社 | Film forming method and storage medium |
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2021
- 2021-01-13 CN CN202180012420.XA patent/CN115087624B/en active Active
- 2021-01-13 JP JP2022509286A patent/JP7397169B2/en active Active
- 2021-01-13 WO PCT/JP2021/000768 patent/WO2021192500A1/en active Application Filing
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| CN86103451A (en) * | 1985-05-22 | 1986-12-03 | 古河电气工业株式会社 | Thermal treatment unit and method of operation thereof |
| JPH0421535A (en) * | 1990-05-16 | 1992-01-24 | Furukawa Electric Co Ltd:The | Preparation of optical fiber preform |
| JPH09157850A (en) * | 1995-11-30 | 1997-06-17 | Nec Corp | Chemical vapor growth method |
| JP2003137584A (en) * | 2001-11-01 | 2003-05-14 | Furukawa Electric Co Ltd:The | Method and device for heat treatment of optical fiber preform |
| JP2009292658A (en) * | 2008-06-02 | 2009-12-17 | Sumitomo Electric Ind Ltd | Dehydration sintering apparatus for porous glass preform and exhaust control method |
| JP2015000839A (en) * | 2013-06-18 | 2015-01-05 | 住友電気工業株式会社 | Optical fiber manufacturing method and device |
| JP2017088458A (en) * | 2015-11-13 | 2017-05-25 | 住友電気工業株式会社 | Dehydration sintering device for porous glass preform, and dehydration sintering method |
Also Published As
| Publication number | Publication date |
|---|---|
| WO2021192500A1 (en) | 2021-09-30 |
| JPWO2021192500A1 (en) | 2021-09-30 |
| JP7397169B2 (en) | 2023-12-12 |
| CN115087624B (en) | 2024-01-02 |
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